Quantum computing based on spin qubits formed by phosphorus donors in silicon [1]} is an attractive approach for large scale implementation of quantum information processing. Some of the milestones achieved to date include single shot spin readout [2]}, the demonstration of single qubits based on both electron [3]} and nuclear [4]} spins, the fabrication of donor based devices in silicon based on scanning tunnelling microscope (STM) techniques [5]}, [6]}, the post-fabrication pinpointing of their locations in silicon with the exact lattice site precision [7]}, and a direct two-electron SWAP operation [8]}. With ongoing experimental efforts focused on increasing the number of qubits in quantum devices and achieving control with high fidelities, the challenges associated with scale-up and the design of a universal quantum computer architecture incorporating quantum error correction come into sharper focus.
